1. Field of the Invention
The present invention relates to a method for making tubing for an automotive heat exchanger.
2. Disclosure Information
Designers of heat exchangers must consider a number of interconnected performance factors. For example, high heat transfer efficiency is promoted by turbulent flow within the fluid conducting tubes of the heat exchanger. However, such turbulence is usually achieved only at the cost of a high pumping loss, which may necessitate the use of considerable power to move fluid through the heat exchanger device. If, on the other hand, fluid is allowed to flow through the heat exchanging tubes in a quiescent manner, stratification will occur and the efficiency of the unit will be diminished.
Heat exchanger designers have employed a variety of methods for increasing turbulent flow through the tubes of a heat exchanger. One familiar technique involves the insertion of an additional element into the tube so as to promote turbulent flow. For example, U.S. Pat. No. 2,096,272 discloses an inserted turbulence promoting device. This type of turbulence promoting element suffers from a common drawback inasmuch as additional expense in the form of both labor and material is required to insert the turbulator strip into the tube assembly. In this type of assembly, the turbulator strip is pushed down the longitudinal length of the tube member. Scrap often occurs because of crimping of the turbulator while being pushed through the tube member.
Heat exchanger designers have attempted to avoid drawbacks associated with separate turbulator inserts by providing integral turbulence promoting features in heat exchanger tubes. For example, U.S. Pat. No. 1,881,610 discloses a heat exchanger tube structure in which the tube wall is worked in order to provide the turbulence promoting feature such as a plurality of indentations formed in the wall. Such a structure suffers from two potential drawbacks. First, in the event that the tube wall is of sufficient thickness so as to withstand the roughening process without resulting in any distortion of the outer surface of the tube, the heat transfer characteristics of the tube will be somewhat impaired by the thickness of the wall itself. Furthermore, the expense of the tube material will be increased because of the thicker wall.
It is an object of the present invention to provide a method for making a heat exchanger tube which provides good heat transfer characteristics and may be easily processed during the assembly thereof.
It is an advantage of the present invention that the heat exchanger tube according to this invention may be fabricated without additional labor costs associated with other types of turbulence promoting heat exchanger tubes.
Other objects, features and advantages of the present invention will become apparent from the following drawings and detailed description.